What condition are your shells in, your ammo? I've owned two mossies that did the same thing. However, they don't malfunction with new ammo, just old rusty stuff after I've carried it out in the salt marsh. I just chunk it if it's too bad, but occasionally one with some rust on it sticks in the action and I have to take my multi-tool to it in the field to get the round out. It's irritating. I wish they still made Activ shells, no metal on them to rust. I can't carry rounds afield more'n a couple of trips and let them sit up long or they'll rust. I'm currently experimenting with various lubes and waxes trying to keep the rust down on the ammo. I'd get mad at the gun, but I think the same thing would likely happen in most any repeating shotgun. If the round gets TOO bad, firing it causes it to split, not good.
Plastic shot shells cured the swelling paper problem, but has done nothing for the rusting "brass", which isn't brass at all.
